No faces appearing on my model in UV editor
it looks like you have turned off 'Show overlays' by accident.
Without it turned on:

With it turned on:

This function is there to easily check your scene without all the assisting overlay graphics. For instance, when you're working in Eevee and you want to see the final result while moving through your scene, you can easily turn the overlays off to get the ultimate viewing experience.
Hope this helps!